Self-Assemble and In Situ Formation of Ni_{1− x}Fe_xPS₃ Nanomosaic-Decorated MXene Hybrids for Overall Water Splitting

Herein, the authors present the development of novel 0D–2D nanohybrids consisting of a nickel-based bimetal phosphorus trisulfide (Ni_{1− x}Fe_xPS₃) nanomosaic that decorates on the surface of MXene nanosheets (denoted as NFPS@MXene). The nanohybrids are obtained through a facile self-assemble process of transition metal layered double hydroxide (TMLDH) on MXene surface; followed by a low temperature in situ solid-state reaction step. By tuning the Ni:Fe ratio, the as-synthesized NFPS@MXene nanohybrids exhibit excellent activities when tested as electrocatalysts for overall water splitting. Particularly, with the initial Ni:Fe ratio of 7:3, the obtained Ni_0.7Fe_0.3PS₃@MXene nanohybrid reveals low overpotential (282 mV) and Tafel slope (36.5 mV dec⁻¹) for oxygen evolution reaction (OER) in 1 m KOH solution. Meanwhile, the Ni_0.9Fe_0.1PS₃@MXene shows low overpotential (196 mV) for the hydrogen evolution reaction (HER) in 1 m KOH solution. When integrated for overall water splitting, the Ni_0.7Fe_0.3PS₃@MXene || Ni_0.9Fe_0.1PS₃@MXene couple shows a low onset potential of 1.42 V and needs only 1.65 V to reach a current density of 10 mA cm⁻², which is better than the all noble metal IrO₂ || Pt/C electrocatalyst (1.71 mV@10 mA cm⁻²). Given the chemical versatility of Ni_{1− x}Fe_xPS₃ and the convenient self-assemble process, the nanohybrids demonstrated in this work are promising for energy conversion applications.